Introduction:
Pregnant women with diabetes often show low levels of physical activity (PA) and high sedentary behavior (SED). Longitudinal studies with objective measures are needed to understand the relationships of daily PA with daily and next-day blood glucose (BG).
Hypothesis:
Increased steps or moderate to vigorous PA (MVPA) and decreased SED are linked with lower post-meal BG and next day fasting BG in pregnant women.
Methods:
Participants were 10 pregnant women with diabetes [mean age= 29.3 (SD= 3.6); mean gestational age= 21.9 (SD= 3.9); 90% (9 of 10) Latina] enrolled in a 12-week pilot PA intervention. Participants self-reported demographic and BG data (morning fasting BG, up to 3 daily post-meal BGs). Steps, MVPA (mins/day), and SED (mins/day) were measured using a Fitbit Alta HR. Participants had on average 49 (range: 21 to 77) days with valid PA and BG data, for a total of 469 observations. Multi-level models (MLMs) were fit to examine mean and day-level effects of steps, MVPA, and SED on post-meal and next-day fasting BG after adjusting for age, gestational age, education, and participant mean PA or SED. Due to the small sample size, effect sizes are emphasized in results instead of statistical significance.
Results:
The mean post-meal BG was 122.5 mg/dL and mean fasting BG was 92.81 mg/dL. After adjustment, an increase of mean steps by 1000 was linked to a lower mean post-meal BG by 11.79 mg/dL (p=0.22) and fasting BG by 7.26 mg/dL (p=0.54), though neither between effect was statistically significant. The within-individual effects of daily steps on post-meal and fasting BG were very small and non-significant (b=-1.78; p=0.59; b=0.72; p=0.30, respectively). A 1-minute increase in mean MVPA was associated with a slight increase in mean post-meal BG by 1.53 mg/dL (p=0.07). The within-individual effect of daily MVPA on daily post-meal BG was negligible and non-significant (b=-0.39, p=0.51). Between-individual effects showed SED had small, positive, non-significant associations with post-meal BG. Specifically, per 60-minute mean SED increase, mean post-meal BG increased by 1.02 mg/dL (p=0.44). Within-individual daily SED increases of 60 minutes were associated with increases of 1.87 mg/dL (p=0.63) in daily post-meal BG. MVPA and SED were not associated with fasting BG.
Conclusions:
Greater mean steps were linked to lower post-meal and fasting BG while greater SED and MVPA were linked to greater post-meal BG. However, within individual daily increases in MVPA and decreases in SED, were protective for post-meal BG, while controlling for individual mean MVPA and SED. Most effect sizes were small and results were not statistically significant in part due to the small sample size. Participants generally had well-controlled post-meal and fasting BGs, so results may not be generalizable to larger populations.
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